Hydraulic shock absorber



May 19, 1931. F. H. RoYcE 1,805,924

HYDRAULIC SHOCK BSORBER Filed March 1ll 1927 2 SheetsfSheet 1 nfrederic/ E qyce @Wynn/f' uw) 'May 19, 1931. F. H. RoYcE HYDRAULIC sHocxABsoRBER Filed March 11, 1927 2 sheets-sheet '2 v 'aIlllIlllllllll/lll//I Patented May 19, 1931 @UNITED STATES' yPpfrENfl;OFFICE FREDERICK HENRY ROYCE, OF WEST WITTERING, NEAR CHICHESTER,ENGLAND, AS- SIGNOR TO ROLLS lROYCE LIMITED, F DERBY, ENGLAND HYDRAULICSHOCK ABSORBER Application filed March 11, 1927, Serial No. 174,619, andin Great Britain March 31, 1926.

This invention has reference to hydraulic shock absorbers in which apiston in a closed cylinder is moved axially by the shocked member,there is a liquid compression chamber at each side of the piston, andthe liquid is forced (when the instrument .is actuated) from thecompression chamber, in which it is subjected to pressure, by arrangedpathways into the other compression chamber.

Difficulty is experienced in hydraulic shock absorbers in adjusting theresistances offered by or inthe pathways, owing to the variation ofviscosity ofthe liquid used, due to changes of temperature. The objectof the invention is to overcome this diiliculty. and

secure other advantages. The principle of this invention liesmainly inminimizing the effect of the. variation of viscosity, and rendering itof comparatively little moment. To that end the conduits or passage waysfrom one compression chamber to the other are according to this of themost simple and direct nature and are controlled by spring loaded valvespreferably of comparatively large area.

According to this invention the conduits or passage Ways are constructedin the piston, and preferably the valve controlling the liquid-pathwayfrom one chamber tol the other are made concentric with the valve orvalves controlling the liquid-pathway in the opposite direction. Thisconcentric arrangement may be made by arranging one valve concentricwith, or with its axis parallel tov the axis of the piston, its springreacting between the valve and the wall of the piston, and arranging theother valve concentric with and within the first mentioned valve.

In the accompanying drawings an example of my invention is illustrated.

Fig. 1 is a sectional elevation of the shock absorber, Fig. 2 a partsectional plan on the line 2-2 in Fig. 3, Fig. 3 an end sectionalelevation on the line 3-3 in Fig. 1, Fig. 4 an end elevation of thepiston and valve from the direction of the arrow marked 4 in Fig. 1, andFig. 5 a section of the outer valve only (the inner valve being removed)on the line 5--5 on Fig. 1.

Fig. 6 is a vertical, longitudinal sectlonal view, on an enlarged scale,of the piston at one end thereof, showing the valve arrangement.

Fig. 7 is a horizontal sectional view, on an enlarged scale, of thepiston and its associate valves.-

a is the cylinder block comprising the cylinder a0 in which the pistonreciprocates, an elongated chamber a1 above the cylinder and extendingthe whole length of the same, an elliptical upstanding part a2, aprojecting cylindrical part a3, a reservoir a4 which is connected withthe space a1 above the cylinder, extends down one side of the cylinderto the under ypart thereof, and there merges into avcylindric'alprojection (see Fig. 3). a5 is an end cover to bealixed when the pistonis in position, and q.6 is a cover to be aiiixed when the working partsare assembled, a7 is a cylindrical plug closing the open end of the saidcylindrical projection, a8 is a gauze strainer soldered to the plug a7,a is a conduit drilled through the Wall of the cylinder block and intothe cover a5, am and all are two conduits by which fluid can pass fromthe conduit a9 into one of the compression chambers, controlled by aone-way ball valve a, there being similar conduits and a similar valvefrom the conduit a" to the other compression chamber. The cylindricalplug al, as illustrated in Figs. 1 and 3, is formed with threecircumferential grooves With openings int-o the, interior ofthe plug.Two of these grooves with their openings are covered with the gauzestrainer through which direct communication is had with the reservoira4. The third groove and openings lead to the two halves of the conduita, which -lead to the drilled holes al and all, controlledl by thevalves a, leading into either end of the cylinder. At the top of thecylinder there is an elliptical hole als for the lever hereinafterreferred to to pass through. b is a shaft rotating in the cylindricalpart a3, operatively connected to the shocked member to be restrained bylever b1 and secured inthe cylindrical part. b2 is a cap forming ahousing for a packing gland secured by studs and Y nuts b3 and b". Theshaft b has a square part 55,6 isa bifurcated lever mounted on thesquare part of the shaft, and clamped thereto by means of a bolt b",passing through perforated bosses formed on the jaws of the lever, 128are links pivotally hinged to the said l one end of the piston to thesaid diaphragm,

05 are-holes drilled down such bosses into the chamber c3, so that thechamber c3 is in free communication with the compression chamber at oneend of the piston, c6 is a hollow piston valve normally closed at oneend, and permanently open at the other, seating on a conical surface c?,formed on the circular orifice of the chamber, c3, e8 (see Figure 4) areradial webs extended from the interior of the piston forming guides forthe hollow piston valve, 09 is an annular shouldered member inserted inthe circular space between the webs, and located by a split ring 010 ingaps formed in each of the webs, 011 is a coil spring reacting betweenthe hollow valve and the shoulder of the member 09. There are four holes012 in the wall of the hollow valve through which liquid can freelypass, cl3 is a hole through the bottom of the hollow piston to enableany oil which may collect there to pass out. d is a mushroom valveseating on a conical opening all in the normally closed end of thehollow valve, d2 is a guide for the mushroom valve supported from thewall of the hollow valve by ribs d3, d4 isa nut engaging a thread on theend of the spindle of the mushroom Valve, d5 is a spiral spring reactingbetween the said nut, and the said ribs projected from the wall of thehollow valve. e and e1 are'conduits for an air leak through which aircan escape from one of the compression chambers into the space al,controlled by the one-way ball valve e2. The cross section area throughthis air leak is predetermined and fixed by the flange e3. In theapparatus illustrated the valves c and d are shown as concentric withone another, but with their axis above the axis of the piston. Theobject of placing the valves near the top of the from that endof the airleak.

The functioning of the ap aratus is as follows, the compression cham ersbeing filled with liquid, and the reservoir supplied with a suitablequantity of like liquid. If the piston is moved to the right, liquidfrom the right compression chamber will be forced, always subject toresistance of the spring d, through the valve d into the chamber c3 andpiston remote from the piston is to facilitate the escape of `air flatannular thence to the left compression chamber. If the piston is movedto the left, liquid from the left chamber will be forced, alwaysresisted by the spring c, through the valve c, and thence through theholes 012, andl between the webs cs to the right compression chamber.

With apparatus as described apart from the valves, the liquid can passfreely from one compression chamber to the other and variation ofviscosity due to change in temperature is negligible. The crosssectional areas of each of the valves, and the consequential allowedrange of opening, are such that the valve opening accommodates itself toany such variations of viscosity of the liquid.

It is` to be noticed that there is a difference between the effect of anupward and downward movement of the springs of a car and it has beendetermined by experiment that, While in both movements a damping-isdesirable, the car will ride more smoothly if the axle bev allowed toapproach the frame more easily than to move away from it. Hence, it isdesirable that the valves shall. be'spring loaded with springs olieringdifferent resistance.

`What I claim is l. A hydraulic shock absorber of the type comprising aclosed cylinder, a double-ended piston within such'cylinder, acompression chamber on each side of the piston, restricted means ofcommunication consisting of pathways and orifices from one chamber tothe other, and means whereby the piston is moved to and fro by theshocked member to be restrained, characterized in that the piston ishollow, and further comprises a diaphragm with the central orificeextending across the piston, means including .pathways in the body ofthe piston whereby each compression chamber is in free communicationwith the space on its.side of thediaphragm immediately adjoining thediaphragm, a moving tubular member normally closed at one end andpermanently open at the other, seating at its normally. closed end onthe orifice in the diaphragm, radial ribs projecting inwardly from thepiston wall extending from the diaphragm for a suitable distance in thedirection of, and constituting axial guides for, the tubular member,notches in the inner edges of the said ribs beyond the range of movementof the tubular member forming an annular recess,

member in the circular space within the ribs abutting against the splitring, a coil spring reacting between the said annular member and thetubular member urging the tubular member to close the said orifice, acentral hole in the normally closed end of the tubular' member, a sleeveguide within the tubular member co-axial with, but spaced away from thesaid hole, and supported at its end nearer to the said hole by ribsextended from the wall of the tubular a split ring in such notches, a

member, a mushroom member seating on the outer side of the said hole andthe stem thereof projecting through the hole and through and for adistance beyond the sleeve guide, a ithread on the end of the said stem,a nut screwed on the said thread and a coil spring reacting between thenut, and the said ribs urging the mushroom member to close the saidhole. 2. A hydraulic-shock absorber of the type in which the damping.takes place in any lmovement of the piston and the oil displaced passesdirectly to and fro between the compression chambers comprising a closedcylinder, a double-ended piston twithin such cylinder, a compressionchamber on each side of the piston, restricted means of communicationconsisting of pathways and orifices from one chamber to the other andmeans whereby the piston is moved to and :Ero by the shocked member tobe restrained, characterized in that vthe means of communication isthrough the body of the piston, two spring loaded valves of whichoneopens under presf 2,5 sure in one direction and the other underpressure in the otherl direction, and each offers a predeterminedresistance, normally to close'the means of communication, and means forreplenishing the compression l chambers including a reservoinof liquid,a

'conduit leading from such reservoir to one of the Y compressionchambers, a one-Way valve controlling suchconduit, another con.- duitleading from the reservoir to the other compression chamber, a one-Wayvalve controllin such last mentioned conduit, and an air lea from thetop of one' of the compres# sion chambers to the reservoir;

In witness whereof I have signed this speci- 40 ication.

FREDERICK HENRY ROYCE.

